376 
DUNCAN S. JOHNSON 
forms a complete jacket about the embryo and is commonly capped by 
the pushed-off stylar remnant (fig. iii). Somewhat later the tip of 
the radicle bursts through the micropylar end of the endosperm and 
continues to grow outward till the root cap, the primary root and at 
length the hypocotyl are differentiated and exposed (fig. 1 12). During 
all this time the endosperm remains tightly clasping about the cy- 
lindrical primary axis of the plantlet like a collar (fig. 112, and Johnson, 
1902, fig. 36). Ultimately the cotyledons slip out of the clasping 
endosperm and spread apart to allow the expansion of the rudiments of 
the plumule at the stem growing point, just as in P. pellucida (Johnson, 
1902, figs. 38, 39). The outer surface of the embryo itself shows at the 
very tip of the root, at a time shortly before the cotyledons have es- 
caped, a delicate root cap about two diameters long. Behind this 
there are scores of root hairs of lengths reaching up to a millimeter or 
more. Then, at the upper limit of root hairs, there is an abrupt 
swelling of the axis to form the hypocotyl, which has nearly twice the 
diameter of the root. The surface of the usually sharply bent hy- 
pocotyl is sprinkled with hydathodes and with still more abundant 
oil-containing cells but no stomata are visible at this early stage (fig. 
112). The cotyledons at the time of their escape have an epidermis of 
rather wavy margined cells with stomata, hydathodes and oil cells 
scattered among them. 
The study of sections of the embryo during germination shows 
that the embryo is differentiated in the usual way from the rounded cell 
mass present in the ripe seed. This globular body elongates, and 
broadens at the chalazal end. Then two lateral prolongations of this 
same end give rise to the cotyledons and leave between them a de- 
pressed area from which the stem growing point is soon formed (fig. 
III. See also Johnson, 1902, figs. 34, 35). The vascular system 
consisting of a single axial bundle from the tip of the root to the base of 
the cotyledons, is developed in the usual way, so far as followed. 
The mode of transition was not followed out because of the lack of 
satisfactory series of sections of this region. The behavior of the' 
endosperm during germination is very similar to that already pointed 
out by the writer in Saururus and in other Piperaceae (Johnson, igoob, 
figs. 7-10, and 1902, figs. 30-39). The growth of the endosperm is 
more active at the sides and it elongates most in the direction of the 
axis of the seed (fig. iii). The micropylar end of the endosperm 
closes together partially, at first, about the tip of the radicle. The 
